Metadynamics (MetD) bias, in kcal mol⁻¹, necessary for converting, at 650 K, HCHO and HCN into glycolonitrile (reaction (1)). As reported in the legend, red crosses, green crosses, and blues asterisks correspond to simulations conducted by deposing gaussian heights of the bias equal to 2.4, 4.8, and 7.2 kcal mol⁻¹, respectively. Since the simulation employing heights equal to 2.4 kcal mol⁻¹ was “slow” enough (yielding a bias profile similar to the choice 4.8 kcal mol⁻¹), such a value has been chosen in order to repeat, three additional times, reaction (1) by means of AIMD + MetD techniques.